Packing method and packed object

ABSTRACT

A packing method makes it possible to achieve, at a low cost, both reduction of a rise in temperature of a black-based foamed product and stacking stability. The packing method for a package includes the steps of setting, on a black-based foamed product that is stacked in one or more layers on a pallet, a cover board such that the cover board covers a main surface of an uppermost layer of the black-based foamed product, and covering, with a black-based stretch film, an outer periphery corresponding to side surfaces of the black-based foamed product.

TECHNICAL FIELD

One or more embodiments of the present invention relate to a method for packing a foamed molded product and a package.

BACKGROUND

Bead-foamed molded products (foamed products) have been used in a wide variety of applications such as packing materials, building materials, and vehicle parts, since the bead-foamed molded products are excellent in shock-absorbing properties and lightweight properties and can be designed to have any shape in accordance with an intended use. The bead-foamed molded product is manufactured by, for example, pre-expanding thermoplastic resin particles to prepare pre-expanded particles and molding the pre-expanded particles in a mold, in a mold-processing factory. The bead-foamed molded products have been widely used in a variety of forms, such as a block form and a box form since the bead-foamed molded products can have a variety of shapes through foam-molding in accordance with molds used for in-mold molding.

Bead-foamed molded products containing carbon (carbon-containing bead-foamed molded products) are excellent in heat-insulating properties, compared with typical bead-foamed molded products. Thus, in recent years, there has been an increasing demand for such a carbon-containing bead-foamed molded product as a heat insulator for housing.

For example, Patent Literature 1 discloses, as a packing film used for a conventional method for packing a bead-foamed molded product, a packing film made from a thermoplastic resin film which contains a white pigment or a metal powder and which is provided with small through holes. In addition, Patent Literature 2 discloses a packing method in which white paper is used for packing, as a method for packing a black-based bead-foamed molded product.

PATENT LITERATURE

[Patent Literature 1]

Japanese Patent Application Publication, Tokukaihei, No. 5-262370

[Patent Literature 2]

Japanese Patent Application Publication, Tokukai, No. 2019-202786

The method disclosed in Patent Literature 1 is intended for a foamed product coated with a low-melting point resin, and the method assumes packing a bead-foamed molded product (foamed product) which does not contain carbon, that is, which does not have a black-based color. Thus, the method disclosed in Patent Literature 1 has difficulty in reducing a rise in temperature of a foamed product having a black-based color in a package in a case where the foamed product which has a black-based color and which more easily absorbs heat than a white foamed product is packed. In addition, the packing method disclosed in Patent Literature 2 has a difficulty in stacking stability of a packed material.

In consideration of these circumstances, an aspect of one or more embodiments of the present invention provides a method which is for packing a foamed product and which can achieve, in a case where a foamed product having a black-based color is packed, both stacking stability and reduction of a rise in temperature of the foamed product having a black-based color.

SUMMARY

That is, an aspect of one or more embodiments of the present invention includes configurations below.

A method for packing, into one package, a black-based foamed product which has a rectangular shape, which is made of a thermoplastic resin, and which has a lightness index L* of less than 65, the method including the steps of: setting, on the black-based foamed product that is stacked in one or more layers on a pallet, a cover board such that the cover board covers a main surface of at least an uppermost layer of the black-based foamed product, the cover board having a larger dimension than the black-based foamed product; and covering, with a black-based stretch film, an outer periphery corresponding to side surfaces of the cover board and an outer periphery corresponding to side surfaces of the black-based foamed product such that a gap is provided between the black-based stretch film and the black-based foamed product.

A package including: a black-based foamed product stacked in one or more layers on a pallet and made of a thermoplastic resin, the black-based foamed product having a rectangular shape and having a lightness index L* of less than 65; a cover board which is set on the black-based foamed product such that the cover board covers a main surface of at least an uppermost layer of the black-based foamed product, the cover board having a larger dimension than the black-based foamed product; and a black-based stretch film covering an outer periphery corresponding to side surfaces of the cover board and an outer periphery corresponding to side surfaces of the black-based foamed product such that a gap is provided between the black-based stretch film and the black-based foamed product.

An aspect of one or more embodiments of the present invention makes it possible to achieve, in a case where a foamed product having a black-based color is packed, both stacking stability and reduction of a rise in temperature of the foamed product.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view schematically illustrating a configuration of a package in accordance with one or more embodiments of the present invention.

FIG. 2 is a side view schematically illustrating a configuration of a package in accordance with one or more embodiments of the present invention.

FIG. 3 is a side view schematically illustrating a configuration of a variation of the package illustrated in FIG. 2 .

DETAILED DESCRIPTION

The following will describe one or more embodiments of the present invention, but one or more embodiments of the present invention are not limited to this. One or more embodiments of the present invention are not limited to any of configurations described below, but can be altered within the scope of the claims. One or more embodiments of the present invention also encompass, in their technical scope, any embodiments or example derived by combining technical means disclosed in differing embodiments or Examples. Further, it is possible to form a new technical feature by combining technical means disclosed in various embodiments. Note that all academic and patent literatures cited in the present specification are incorporated herein by reference. Further, any numerical range expressed as “A to B” herein means “not less than A and not more than B (i.e., a range from A to B which includes both A and B)” unless otherwise stated. Further, the drawings are shown so as to be easily understood when referred to together with the following descriptions. The drawings are not necessarily illustrated to have a constant scale ratio.

[1. Technical Idea of One or More Embodiments of the Present Invention]

Foamed products having a black-based color (black-based foamed products), especially, bead-foamed molded products containing carbon (carbon-containing bead-foamed molded products) which can act as radiative heat transfer inhibitors are excellent in heat-insulating properties. Thus, in recent years, such foamed products have been used in a wide variety of applications such as heat insulators for housing.

In a case where a foamed product having a black-based color is used outdoors such as at a construction site, the foamed product having a black-based color is transferred to the site in a packed state. In some cases, the foamed product having a black-based color is kept outdoors in a packed state until the foamed product is used. However, a foamed product having a black-based color easily absorbs heat, and thus a surface temperature of the foamed product easily rises. In this arrangement, a package with use of a bag made of polyolefin has been used as a simple package for protection from rain and dirt. In such a simple package, the bag is transparent and thus transmits sunlight, so that a temperature in the package may rise extraordinarily. It has been found that this is a reason why deformation of a foamed product having a black-based color occurs as a result of heat absorption and melting of the foamed product having a black-based color in a case where the foamed product having a black-based color is packed with use of a bag made of polyolefin.

As a method for packing a foamed product in a manner that may prevent such deformation caused by sunlight, suggested is a method for packing a foamed product with use of a thermoplastic resin film that has been subjected to a light-blocking measure, as disclosed in Patent Literature 1. However, such a conventional packing method is intended for white foamed products which absorb less heat than foamed products having a black-based color, and with the conventional packing method, for example, reduction of a rise in temperature is insufficient in a case where foamed products having a black-based color are packed. In addition, even in a case where packing is carried out with use of the thermoplastic resin film that has been subjected to the light-blocking measure, a temperature of the thermoplastic resin film itself rises, so that a surface of the foamed product in contact with the thermoplastic resin film may melt and deform.

Patent Literature 2 discloses a method for packing a foamed product having a black-based color with use of white paper. However, a package with paper lacks stretchability and thus has room for improvement in stacking stability of the foamed product, such as improvement concerning easy occurrence of stack collapse.

In addition, another method proposed is a method in which sunlight is blocked by covering a packed foamed product (packed material) with a blue poly tarp or the like. However, it is difficult to carry out this method thoroughly at a construction site. Further, such a large-scale packing with use of the blue poly tarp or the like unfortunately leads to a lot of trouble for disposal as well as a high cost.

The foamed product having a black-based color is fragile and is sold and bought at a relatively low price. Thus, it is desired that a method for packing the foamed product having a black-based color is carried out simply and at a low cost and achieves favorable stacking stability in order to prevent breakage during transportation.

In consideration of the circumstances as above, the present inventors have conducted diligent studies for providing a method which is for packing a black-based foamed product and which can achieve, in a case where the black-based foamed product is packed, both stacking stability and reduction of a rise in temperature of the black-based foamed product at a low cost. As a result, the present inventors have achieved one or more embodiments of the present invention.

[2. Method for Packing Black-Based Foamed Product]

The method, in accordance with one or more embodiments of the present invention, for packing a black-based foamed product is a method for packing, into one package, a black-based foamed product which has a rectangular shape, which is made of a thermoplastic resin, and which has a lightness index L* of less than 65, the method including the step of: setting, on the black-based foamed product that is stacked in one or more layers on a pallet, a cover board such that the cover board covers a main surface of at least an uppermost layer of the black-based foamed product, the cover board having a larger dimension than the black-based foamed product; and covering, with a black-based stretch film, an outer periphery corresponding to side surfaces of the cover board and an outer periphery corresponding to side surfaces of the black-based foamed product such that a gap is provided between the black-based stretch film and the black-based foamed product. Hereinafter, “the method, in accordance with the present disclosure, for packing a black-based foamed product” may be also referred to as “the present packing method”.

According to the above configuration, in the step of covering, those outer peripheries corresponding to the side surfaces of the cover board and the black-based foamed product are covered with the black-based stretch film such that a gap is provided between the black-based foamed product and the black-based stretch film. Thus, air is present between the black-based foamed product and the black-based stretch film, so that heat absorbed by the black-based film becomes less likely to be transmitted to the black-based foamed product. Therefore, the above configuration makes it possible to reduce a rise in temperature of the black-based foamed product. Furthermore, it is possible to prevent the black-based foamed product from warping, deforming, or changing in dimension caused by such a rise in temperature.

In addition, according to the above configuration, the black-based stretch film covers the outer peripheries corresponding to the side surfaces of both the black-based foamed product and the cover board for covering the main surface of the uppermost layer of the black-based foamed product. Thus, the black-based stretch film allows the black-based foamed product and the cover board to be kept in contact with each other, so that it is possible to prevent stack collapse of the black-based foamed product and to achieve a package with stacking stability of the black-based foamed product.

As described above, the above configuration makes it possible to achieve, in a case where the black-based foamed product is packed, both the stacking stability and the reduction of a rise in temperature of the black-based foamed product.

(Stacking Step)

The present packing method may include a stacking step of stacking the black-based foamed product in the one or more layers on the pallet. The stacking step may be carried out before a setting step described later or may be carried out after the setting step.

In the stacking step in accordance with one or more embodiments of the present invention, the number of the layers of the black-based foamed product stacked is not limited, provided that the number of the layers is one or more. For example, the number of the layers may be two or more or may be four or more. Here, the “number of layers of the black-based foamed product” can be also said to be the number of black-based foamed products that are stacked one on top of each other.

In the stacking step in accordance with one or more embodiments of the present invention, the method for stacking the black-based foamed product (stacking method) is not particularly limited. In order to prevent stack collapse, interlocking stacking, brick stacking, pinwheel stacking, or split stacking is preferable.

(Setting Step)

The present packing method includes a setting step of setting, on the black-based foamed product that is stacked in the one or more layers on the pallet, the cover board such that the cover board covers a main surface of at least an uppermost layer of the black-based foamed product, the cover board having a larger dimension than the black-based foamed product. The cover board set on the uppermost layer of the black-based foamed product stacked may be herein also referred to as “upper (uppermost) cover board”. Here, the expression “main surface” refers to a surface that is mainly subjected to an action of the cover board, among surfaces which constitute the black-based foamed product. More specifically, the “main surface” refers to an upper surface or lower surface of the black-based foamed product on the premise that a direction in which the black-based foamed product is stacked is an upper-lower direction.

In one or more embodiments of the present invention, the setting step may further include the step of placing the cover board on the pallet. Such a configuration makes it possible to reduce impairment of the black-based foamed product due to dirt while the black-based foamed product is packed. Note that, in a case where the setting step includes the step of placing the cover board on the pallet, the step of placing the cover board on the pallet may be carried out before the stacking step. That is, the black-based foamed product may be stacked on the cover board placed on the pallet. The cover board placed on the pallet may be herein also referred to as “lower (underlay) cover board”.

In one or more embodiments of the present invention, the setting step may further include the step of interposing the cover board between the layers of the black-based foamed product, the layers having been stacked in the stacking step. The step of interposing the cover board between the layers of the black-based foamed product may be carried out before the upper cover board and/or the lower cover board is set or may be carried out after the upper cover board and/or the lower cover board has been set. At least one cover board interposed between the layers of the black-based foamed products may be herein referred to as “middle (center) cover board”.

A structure constituted by the black-based foamed product and the cover board which are stacked on the pallet in the (Stacking step) and the (Setting step), respectively, may be herein referred to as “stack”.

(Covering Step)

The present packing method includes a covering step of covering, with a black-based stretch film, an outer periphery corresponding to side surfaces of the cover board and an outer periphery corresponding to the black-based foamed product such that a gap is provided between the black-based foamed product and the black-based stretch film. Here, the expression “such that a gap is provided between the black-based foamed product and the black-based stretch film” means a state where the black-based stretch film and the black-based foamed product are not in contact with each other.

The covering step in accordance with one or more embodiments of the present invention can be also said to be the step of winding a black-based stretch film around the black-based foamed product and the cover board (stack) which have been stacked on the pallet in the (Stacking step) and the (Setting step), respectively. In this step, the black-based stretch film is wound so as to cover (touch) edge portions of the side surfaces of the cover board and so as to cover entire side surfaces of the stack, that is, so as to prevent the black-based foamed product from being exposed to the outside. The black-based stretch film may be wound for one or more turns (one or more wraps), two or more turns, or three or more turns around the stack. Covering the stack with the black-based stretch film for one or more turns allows the black-based foamed product to have a favorable stacking stability.

In one or more embodiments of the present invention, the gap between the black-based foamed product and the black-based stretch film may be not less than 5 mm. In a case where the gap between the black-based foamed product and the black-based stretch film is not less than 5 mm, it is unlikely that, in a case where the black-based stretch film absorbs sunlight and rises in temperature, the black-based stretch film which has risen in temperature touches the black-based foamed product. This makes it possible to further reduce, for example, melt of the black-based foamed product and a rise in temperature of the black-based foamed product by sunlight.

In the covering step in accordance with one or more embodiments of the present invention, the stack may be covered with another stretch film having a color other than the black-based color, in addition to the black-based stretch film. The stretch film having a color other than the black-based color is not particularly limited but may be, for example, a white stretch film or a transparent stretch film.

[3. Package]

The following will describe in detail a package provided by the present packing method with reference to FIGS. 1 to 3 . FIG. 1 is a cross-sectional view schematically illustrating a configuration in a case where a single foamed product is packed by the present packing method. FIG. 2 is a view schematically illustrating a configuration in a case where a plurality of foamed products are packed by the present packing method. FIG. 3 is a side view schematically illustrating a variation of the package illustrated in FIG. 2 .

As described in FIG. 1 , a package 100 provided by the present packing method includes one layer of a black-based foamed product 1, cover boards 2 a and 2 b, a black-based stretch film 3, and a pallet 4. The cover boards 2 a and 2 b are boards each having a dimension larger than that of the black-based foamed product 1 and are respectively set above and below the black-based foamed product 1. Note that it is sufficient that the package 100 includes the cover board 2 a that covers an upper surface of at least the black-based foamed product 1.

The package 100 has a structure in which the black-based foamed product 1 configured as above and the cover boards 2 a and 2 b configured as above are stacked on the pallet 4. In addition, the black-based stretch film 3 covers an outer periphery corresponding to side surfaces of the black-based foamed product 1 and outer peripheries corresponding to side surfaces of the cover boards 2 a and 2 b such that a gap is provided between the black-based foamed product 1 and the black-based stretch film 3. This black-based stretch film 3 covers the outer peripheries so as to touch outer periphery portions corresponding to the side surfaces of at least the cover board 2 a.

In the configuration illustrated in FIG. 1 , the black-based stretch film 3 is configured to: be apart from the side surfaces of the black-based foamed product 1; touch the outer peripheries corresponding to the side surfaces of the cover boards 2 a and 2 b; and cover a whole of an upper surface of the cover board 2 a. This improves stacking stability of the black-based foamed product 1 in the package 100. In view of the stacking stability of the black-based foamed product 1, it is sufficient that the black-based stretch film 3 touches the outer periphery corresponding to the side surfaces of at least the cover board 2 a and covers edge portions of the upper surface of at least the cover board 2 a. Note that, in a stacking structure, a direction in which the pallet 4 is set is herein referred to as “bottom (lower layer)”, and a direction opposite to the direction of “bottom” is herein referred to as “top (upper layer)”.

It is sufficient that the package 100 includes at least one layer of the black-based foamed product 1. As illustrated in FIG. 2 , in one or more embodiments of the present invention, a package 100 provided by the present packing method is configured to include black-based foamed products 1 a and 1 b that are in respective two layers. The package 100 illustrated in FIG. 2 includes the black-based foamed products 1 a and 1 b, cover boards 2 c, 2 d, and 2 e, and a black-based stretch film 3, and a pallet 4.

The cover board 2 c covers an upper surface of the black-based foamed product 1 a in an upper layer. In addition, the cover board 2 d is interposed between the black-based foamed products 1 a and 1 b that are stacked. Further, the cover board 2 e covers a lower surface of the black-based foamed product 1 b in a lower layer. A stack of the black-based foamed products 1 a and 1 b and the cover boards 2 c, 2 d, and 2 e, which is configured as above, is set on the pallet 4. Note that it is sufficient that the package 100 illustrated in FIG. 2 includes the cover board 2 c that covers the upper surface of at least the black-based foamed product 1 a in an uppermost layer.

The black-based stretch film 3 covers outer peripheries corresponding to side surfaces of the black-based foamed products 1 a and 1 b and outer peripheries corresponding to side surfaces of the cover boards 2 c, 2 d, and 2 e such that a gap is provided between the black-based stretch film 3 and each of the black-based foamed products 1 a and 1 b. This black-based stretch film 3 covers the outer peripheries so as to touch outer periphery portions corresponding to the side surfaces of at least the cover board 2 c.

In the structure illustrated in FIG. 2 , the black-based stretch film 3 is configured to: be apart from the side surfaces of the black-based foamed products 1 a and 1 b; touch the outer peripheries corresponding to the side surfaces of the cover boards 2 c, 2 d, and 2 e; and cover a whole of an upper surface of the cover board 2 c. This improves stacking stability of the black-based foamed products 1 a and 1 b in the package 100. In view of the stacking stability of the black-based foamed products 1 a and 1 b, it is sufficient that the black-based stretch film 3 touches the outer periphery corresponding to the side surfaces of at least the cover board 2 c and covers edge portions of the upper surface of the cover board 2 c.

The package 100 illustrated in FIG. 3 has a configuration differing from that illustrated in FIG. 2 in that the package 100 illustrated in FIG. 3 does not include a cover board interposed between the black-based foamed products 1 a and 1 b. Specifically, in the package 100 illustrated in FIG. 3 , a cover board 2 f covers an upper surface of a black-based foamed product 1 a in an upper layer. In addition, a cover board 2 g covers a lower surface of the black-based foamed product 1 b in a lower layer. The black-based foamed products 1 a and 1 b are in a direct contact with each other, and a cover board interposed between the black-based foamed products 1 a and 1 b is absent.

The package 100 in accordance with one or more embodiments of the present invention can be said to be a package including: a black-based foamed product 1 stacked in one or more layers on a pallet 4 and made of a thermoplastic resin, the black-based foamed product 1 having a rectangular shape and having a lightness index L* of less than 65; a cover board 2 which is set on the black-based foamed product 1 such that the cover board 2 covers a main surface of at least an uppermost layer of the black-based foamed product 1, the cover board 2 having a larger dimension than the black-based foamed product 1; and a black-based stretch film 3 covering an outer periphery corresponding to side surfaces of the cover board 2 and an outer periphery corresponding to side surfaces of the black-based foamed product 1 such that a gap is provided between the black-based stretch film 3 and the black-based foamed product 1.

The following will describe in detail constituent materials of the package 100 in accordance with one or more embodiments of the present invention.

(Black-Based Foamed Product 1)

The black-based foamed product 1 in accordance with one or more embodiments of the present invention is not particularly limited, provided that the black-based foamed product 1 is a black-based resin foamed molded product having a lightness index L* of less than 65 and that the black-based foamed product 1 is a bead-foamed molded product obtained by pre-expanding and molding expandable thermoplastic resin particles or is a bead-foamed molded product obtained by foam-molding thermoplastic resin expanded particles. The black-based foamed product 1 may be constituted by a single black-based resin foamed molded product having a lightness index L* of less than 65 or may be constituted by two or more black-based resin foamed molded products which are stacked on top of each other and each of which has a lightness index L* of less than 65.

The thermoplastic resin which constitutes the expandable thermoplastic resin particles or the thermoplastic expanded particles is not particularly limited. Examples of such a thermoplastic resin include: styrene-based resins such as polystyrene (PS), a styrene-acrylonitrile copolymer (AS), a styrene-(meta)acrylic acid copolymer (heat-resistant PS), a styrene-(meta)acrylic acid ester copolymer, a styrene-butadiene copolymer (HIPS), a terpolymer of N-phenylmaleimide-styrene-maleic anhydride, and an alloy (IP) of any of these substances and AS; vinyl-based resins such as polymethylmethacrylate, a polyacrylonitrile-based resin, and a polyvinyl chloride-based resin; polyolefn-based resins such as polypropylene, polyethylene, an ethylene-propylene copolymer, an ethylene-propylene-butene terpolymer, and a cycloolefin-based (co)polymer, and a rheologically controlled polyolefin-based resin in which a branched structure or a crosslinked structure is introduced in any of the foregoing polyolefin-based resins; polyamide-based resins such as nylon 6, nylon 66, nylon 11, nylon 12, and MXD nylon; aromatic polyester-based resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; aliphatic polyester-based resins such as a polylactic acid; and engineering plastics such as a polycarbonate resin, a polyphenylene ether-based resin (PPE), a modified polyphenylene ether-based resin (modified PPE), a polyoxymethylene-based resin, a polyphenylene sulfide-based resin, a polyphenylene sulfide-based resin, an aromatic polyether-based resin, and a polyether ether ketone resin. One of these may be used solely. Alternatively, two or more of these may be used in combination. Of these thermoplastic resins, a polystyrene-based resin is preferable since the polystyrene-based resin (i) is relatively less expensive, (ii) can be molded without any special method and with use of, for example, steam at low pressure, and (iii) can achieve an effect of high cushioning and heat-insulating properties. That is, in one or more embodiments of the present invention, the black-based foamed product 1 may be a foamed product made of a polystyrene-based foamed resin.

In one or more embodiments of the present invention, a method for causing the black-based foamed product 1 to have a lightness index L* of less than 65, that is, a method for turning a bead-foamed molded product made of a thermoplastic resin into a black-based color is not particularly limited. Examples of such a method include: a method in which carbon is mixed with expandable thermoplastic resin particles or thermoplastic expanded particles that constitute the bead-foamed molded product; and a method in which a black-based pigment is mixed with expandable thermoplastic resin particles or thermoplastic expanded particles that constitute the bead-foamed molded product. Of these methods, the method in which carbon is mixed with expandable thermoplastic resin particles or thermoplastic expanded particles is preferable since the method can give an excellent heat-insulating property to the black-based foamed product 1. In other words, the black-based foamed product 1 in accordance with one or more embodiments of the present invention may contain carbon.

A carbon content in the black-based foamed product 1 in accordance with one or more embodiments of the present invention is not particularly limited. The carbon content, in 100% by weight of the black-based foamed product 1, may be not less than 2% by weight for improving a heat-insulating property, or not more than 8% by weight for achieving excellent foam-moldability.

Examples of carbon contained in the black-based foamed product 1 include graphite, graphene, active carbon, coke, and carbon black. Of these examples, graphite or carbon black is preferable, and graphite is more preferable since they have an excellent balance between cost and the effect of improving the heat-insulating property.

In one or more embodiments of the present invention, the black-based foamed product 1 may have a lightness index L* of less than 65, less than 60, less than 55, or less than 50. A foamed product having a lightness index L* of less than 65 is black or gray in color. Thus, in a case where the black-based foamed product 1 is packed by a conventional packing method, the black-based foamed product 1 may rise in temperature by, for example, absorbing sunlight and result in melting and deforming. In contrast, in a case where a black-based foamed product 1 is packed by the present packing method, it is possible to reduce the rise in temperature of the black-based foamed product 1. The present packing method thus allows for stably packing and preservation even in the case of the black-based foamed product 1 that has a lightness index L* of less than 65.

The expression “lightness index L*” herein refers to a value of a lightness index L* in CIE1976 L*a*b* color space. For example, the lightness index L* of white is 100, and the lightness index L* of black is 0. The lightness index L* in CIE1976 L*a*b* can be measured, for example, with use of a spectroscopic colorimeter (such as CM-2500d, produced by Konica Minolta, Inc.), and a xenon lump as a light source for measurement at a measurement diameter set to be φ8 mm.

In one or more embodiments of the present invention, a shape of a black-based foamed product 1 is not particularly limited. Examples of the shape include: a rectangular shape; a polygonal shape such as a triangular shape and a hexagonal shape; and a circular shape. In one aspect, the black-based foamed product 1 may be mounted into a wooden panel such as a load-bearing wall panel. The black-based foamed product 1 can be determined to have any shape as appropriate in accordance with a desired application.

In one or more embodiments of the present invention, an expanding ratio of the black-based foamed product 1 may be not less than 60 times. The expanding ratio of not less than 60 times of the black-based foamed product 1 makes it possible to provide a foamed product at a relatively low cost and thus gives an economical advantage.

In a case where such a black-based foamed product 1 with an expanding ratio of not less than 60 times as described above is packed by a conventional packing method such as packing by binding with use of a plastic band or a plastic twine, a corner of the black-based foamed product 1 deforms or breaks at a part where the molded product is in contact with the plastic band or the like. In the present packing method, the black-based foamed product 1 and the black-based stretch film 3 are not in a direct contact with each other, and thus it is possible to pack even such a foamed product without deformation and breakage.

(Cover Board 2)

A cover board 2 in accordance with one or more embodiments of the present invention is not particularly limited. The cover board 2 may be at least one selected from the group consisting of a wooden board, a corrugated board, a plastic corrugated board, and a synthetic resin board containing an expanded material.

With regard to a size of the cover board 2, the width and/or the depth may be larger than an outer size of the black-based foamed product 1, and both the width and the depth are each may be larger than the outer size of the black-based foamed product 1 by not less than 5 mm.

The cover board 2 can have any thickness but is required to have a thickness that can withstand a strength at which the black-based stretch film 3 covers and fixes the cover board 2. Specifically, the cover board 2 may have a thickness of not less than 1 mm, not less than 2 mm, or not less than 3 mm. Alternatively, two or more cover boards 2 may be put on top of each other so as to achieve a desired thickness.

(Black-Based Stretch Film 3)

The black-based stretch film 3 in accordance with one or more embodiments of the present invention is made of a black synthetic resin.

In one or more embodiments of the present invention, a synthetic resin which constitutes the black-based stretch film 3 is not particularly limited. Examples of such a synthetic resin include a polyolefin-based resin, an acrylic resin, and a polyvinyl chloride-based resin. Of these synthetic resins, the polyolefin-based resin is preferable, and especially, a polyethylene-based resin is particularly preferable, since such resins have tensile breaking strength and tensile elongation with which it is possible to achieve a stretching property that allows a packed material to be stably covered.

The polyethylene-based resin is not particularly limited, provided that the polyethylene-based resin is an ethylene homopolymer or a copolymer containing an ethylene as a main component and can be applied as a stretch film. In particular, it is preferable to use a polyethylene-based resin which, when measured at a temperature of 190° C. and under a load of 21.18 N, has a melt flow rate (MFR) of not less than 0.5 g/10 minutes and not more than 7 g/10 minutes. The MFR of the polyethylene-based resin may have a lower limit of not less than 0.7 g/10 minutes or not less than 1.0 g/10 minutes. In addition, the MFR of the polyethylene-based resin may have an upper limit of not more than 5.0 g/10 minutes or not more than 3.0 g/10 minutes. The polyethylene-based resin having a MFR of not less than 0.5 g/10 minutes makes it unlikely that a load imposed on an extruder during extrusion molding is excessive and also makes it unlikely that a problem occurs in dispersibility of carbon black (described later) in a resin. Further, the polyethylene-based resin having a MFR of not more than 7 g/10 minutes makes it unlikely that a problem occurs in film formation stability during formation of a blown film and also makes it unlikely that the film thus formed has an excessively low strength.

The expression “black synthetic resin” herein means a synthetic resin which visually exhibits a dark color having a solar absorptance of not less than 90% in a wavelength range of 380 nm to 720 nm. The wavelength range of 380 nm to 720 nm is expressed as “visible light range”, and light in the range is perceivable with the naked eyes of human. An object having a high absorptance of light in the visible light range exhibits a dark color such as black or gray.

In the present specification, the solar absorptance in the wavelength range of 380 nm to 720 nm can be measured by a method described in (1) to (5) below: (1) A black-based stretch film is prepared as a measurement test piece, and reflectances (spectral reflectances) at respective wavelengths in the wavelength range of 380 nm to 720 nm are measured every 1 nm with use of a self-recording spectrophotometer on the premise that a reflectance of an alumina white substrate is 100%; (2) with use of Appendix 3 of JIS A5759, respective values are calculated by multiplying the spectral reflectances at the wavelengths measured in (1) by respectively corresponding weighting coefficients at the wavelengths, and a solar reflectance is calculated as a sum of the values thus obtained (spectral solar reflectance test method); (3) transmittances (spectral transmittances) at the respective wavelengths are measured, for the measurement test piece in (1), with use of the self-recording spectrophotometer on the premise that the transmittance in a state where the measurement test piece is absent in the self-recording spectrophotometer is 100%; (4) with use of Appendix 3 of JIS A5759, respective values are calculated by multiplying the spectral transmittances at the respective wavelengths measured in (3) by the respectively corresponding weighting coefficients at the wavelengths, and a solar transmittance is calculated as a sum of the values thus obtained; and (5) with use of a resultant value of the solar reflectance and a resultant value of the solar transmittance, the solar absorptance is calculated by the following formula (1):

(Solar absorptance)=100%−(solar reflectance)−(solar transmittance)   (1).

In one or more embodiments of the present invention, a method for turning the black-based stretch film 3 into black is not particularly limited. Examples of such a method include a method in which a pigment is added to a synthetic resin that constitutes the black-based stretch film 3. Addition of a black-based pigment such as carbon black and/or aniline black makes it possible to turn the black-based stretch film 3 into black, that is, allows the black-based stretch film 3 to have a solar absorptance of not less than 90% in the wavelength range of 380 nm to 720 nm. As the black-based pigment, carbon black is particularly preferable in view of cost and handleability.

A pigment (black-based pigment) content relative to the synthetic resin cannot be generally specified since affected by the thickness of a film and a desired light blocking-property, but may be 3.0 parts by weight to 15.0 parts by weight relative to 100 parts by weight of the synthetic resin. In particular, the pigment content may have a lower limit of not less than 5.0 parts by weight, or not less than 6.0 parts by weight. In addition, the pigment content may have an upper limit of not more than 12.0 parts by weight, or not more than 10.0 parts by weight. If the pigment content is not less than 3.0 parts by weight, total light transmittance is low, and decrease of the solar absorptance is reduced. This makes it possible to reduce an excessive rise in temperature of the foamed product even in a case where the foamed product is exposed to sunlight. In addition, if the pigment content is not more than 15.0 parts by weight, scratch resistance and plasticity of the synthetic resin are not affected. Thus, with such a pigment content, it is unlikely that moldability of the black-based stretch film 3 is deteriorated by a decrease in strength and elongation of the black-based stretch film 3, and further it is unlikely that cost increases and/or that a lightweight property deteriorates in accordance with an increase in specific weight.

In one or more embodiments of the present invention, a method for producing a pigment is not particularly limited, and it is possible to use any pigment produced by a conventional method such as a furnace black process, a channel black process, and an acetylene black process. In view of availability, a pigment produced by an oil furnace black process is preferable. In addition, the pigment may have an average particle diameter of not more than 10 μm in order to improve dispersibility in the black-based stretch film 3.

The black-based stretch film 3 in accordance with one or more embodiments of the present invention can be easily produced by molding a resin mixture containing the above-described synthetic resin and pigment through a known method. In order to obtain a uniform film, it is preferable to knead (melt-knead), before molding, the resin mixture in a heated and melted state with use of a kneading machine such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a Brabender, an open roll machine, or a kneader. The mixture melt-kneaded can be molded by any method. Examples of such a method include a method for carrying out a film-forming process by cooled-air blown film molding, T-die film molding or the like. In particular, the method by air blown film molding is preferable since the method is simple and economical.

The black-based stretch film 3 in accordance with one or more embodiments of the present invention may have a thickness of 10 μm to 250 μm, 20 μm to 150 μm, or 25 μm to 100 μm. The black-based stretch film 3 having a thickness of not less than 10 μm can sufficiently absorb the light in the visible light range and thus tends to be able to stably exhibit a dark color. The black-based stretch film 3 having a thickness of not more than 250 μm makes it possible to favorably keep handleability of a packing operation and also makes it unlikely to unnecessarily increase cost.

The black-based stretch film 3 in accordance with one or more embodiments of the present invention satisfies a stretching ratio (hereinafter, also referred to as “stretchability”) of not less than 250% in at least a longitudinal direction. Preferably, the black-based stretch film 3 satisfies a stretching ratio of not less than 250% in a longitudinal direction and a stretching ratio of not less than 150% in a lateral direction in co-axial or sequential biaxial stretching. The stretching ratio of the black-based stretch film 3 is herein a value that is measured, in conformity to ASTM-D-882, by a method as follows: the black-based stretch film 3 is set such that a width thereof is 1 cm and a distance between chucks is 10 cm; the black-based stretch film 3 thus set is pulled upward and downward at a speed of 300 mm/min with use of a tension and compression testing machine (produced by Shimadzu Corporation); and an elongation ratio (%) at breakage of the black-based stretch film 3 is measured. The elongation ratio at the breakage of the black-based stretch film 3 is defined as the stretching ratio (%). Note that the stretching ratio of the black-based stretch film 3 is measured in an atmosphere at 23° C. and 50% RH.

Further, the black-based stretch film 3 in accordance with one or more embodiments of the present invention may have a tensile breaking strength (hereinafter, also referred to as “tensile strength”) of not less than 30 MPa in a longitudinal direction and not less than 15 MPa in a lateral direction. The tensile breaking strength of the black-based stretch film 3 is herein a value that is measured, in conformity to ASTM-D-882, by a method as follows: the black-based stretch film 3 is set such that a width thereof is 1 cm and a distance between chucks is 10 cm; the black-based stretch film 3 thus set is pulled upward and downward at a speed of 300 mm/min with use of a tension and compression testing machine (produced by Shimadzu Corporation); and a strength (MPa) at breakage of the black-based stretch film 3 is measured. The strength at the breakage of the black-based stretch film 3 is defined as the tensile breaking strength (MPa). Note that the tensile breaking strength of the black-based stretch film 3 is measured in an atmosphere at 23° C. and 50% RH.

The black-based stretch film 3 in accordance with one or more embodiments of the present invention has the above-described stretchability and the above-described tensile strength, so that it is possible to prevent film breakage and deterioration in operability when the black-based stretch film 3 is wound, over the cover board 2, around the black-based foamed product 1 on the pallet 4.

In addition, the black-based stretch film 3 in accordance with one or more embodiments of the present invention may have ventilation holes. In the present packing method, when the side wall surfaces of the black-based foamed product 1 placed on the pallet 4 is covered with the black-based stretch film 3, a gap is provided between the black-based foamed product 1 and the black-based stretch film 3. In this arrangement, in a case where the black-based stretch film 3 has ventilation holes, circulation of outside air occurs through the ventilation holes. This can reduce a rise in temperature of a space that forms the gap. As a result, it is possible to further reduce a rise in temperature (for example, surface temperature) of the black-based foamed product 1 covered.

A shape of the ventilation holes included in the black-based stretch film 3 is not particularly limited, but it is preferable to have a hole shape formed as a circular shape (for example, a perfect-circular shape or an elliptical shape) is preferable since such a shape makes it possible to reduce breakage of the black-based stretch film 3 due to stretch.

A hole diameter (diameter) of the ventilation hole included in the black-based stretch film 3 is not particularly limited, but may be 0.2 mm to 5.0 mm, since such a size makes it possible to prevent breakage of the black-based stretch film 3 due to stretch and makes it possible to reduce contamination of the black-based foamed product 1 with dirt such as dust due to ventilation.

An open hole rate of the ventilation holes in the black-based stretch film 3 is not particularly limited, but the open hole rate may be 1% to 20% per unit area. If the open hole rate of the ventilation holes in the black-based stretch film 3 falls within the above-described range, appropriate ventilation can be ensured. This can achieve both reduction of a rise in temperature of the black-based foamed product 1 covered and prevention of contamination of the black-based foamed product 1 due to dust and the like which accompany introduction of outside air through the ventilation holes.

As the black-based stretch film 3 having the ventilation holes, it is possible to use a film which originally includes ventilation holes, or a film which does not originally have ventilation holes and in which ventilation holes are formed by perforation through a known method such as hot needle perforation or punching. Further, the ventilation holes can be arranged in any pattern, and may be arranged in a parallel manner or in a staggered manner.

In the present packing method, the black-based foamed product 1 (and the cover board 2) may be covered with a single-layer film made of one type of the black-based stretch film 3 or may be covered with a multilayer film made of one or more types of the black-based stretch film 3 and optionally another film. For example, an outer periphery of the black-based stretch film 3 covering the outer peripheries corresponding to the side surfaces of the cover board 2 and the black-based foamed product 1 may be further covered with another film (another film may be further wound on the periphery) so that a multilayer film is formed, and the multilayer film may cover the black-based foamed product 1 (and the cover board 2). Note that the expression “multilayer” of the multilayer film means that the multilayer film includes two or more types of films.

In one or more embodiments of the present invention, in a case where the cover board 2 and the black-based foamed product 1 are covered with a multilayer film, it is sufficient that the multilayer film has at least one layer made of the black-based stretch film 3. That is, the multilayer film may include one or more types of the black-based stretch film 3 and one or more types of other films or may include only two or more types of the black-based stretch film 3 and no other films. Such another film which may be included in the multilayer film is not particularly limited but may be, for example, a transparent film or a white film. One type of such a film may be used alone, or two or more types of such a film may be used in combination.

In one or more embodiments of the present invention, in a case where the multilayer film includes the other film, the other film can be also said to be a film that covers, together with the black-based stretch film 3, the outer peripheries corresponding to the side surfaces of the cover board 2 and the black-based foamed product 1. The other film may cover an entire side surface of the black-based stretch film 3 for only one turn (single wrap) or two or more turns. The other film may cover the black-based stretch film 3 for two or more turns since this makes it possible to cut cost of the black-based stretch film.

(Pallet 4)

The pallet 4 serves as a base part when the black-based foamed product 1 and the cover board 2 are stacked. In one or more embodiments of the present invention, the pallet 4 may be made of wood or made of a synthetic resin. Further, a shape of the pallet 4 is not particularly limited. Examples of the shape include a rectangular shape.

In one or more embodiments of the present invention, a size of the pallet 4 is not particularly limited, but can be, for example, the following: a width of 1,100 mm×a length of 1,100 mm×a thickness of 125 mm; or a width of 1,000 mm×a length of 1,200 mm×a thickness of 150 mm.

One or more embodiments of the present invention may be configured as below.

<1> A method for packing, into one package, a black-based foamed product which has a rectangular shape, which is made of a thermoplastic resin, and which has a lightness index L* of less than 65 and, the method including the steps of:

-   -   setting, on the black-based foamed product that is stacked in         one or more layers on a pallet, a cover board such that the         cover board covers a main surface of at least an uppermost layer         of the black-based foamed product, the cover board having a         larger dimension than the black-based foamed product; and     -   covering, with a black-based stretch film, an outer periphery         corresponding to side surfaces of the cover board and an outer         periphery corresponding to side surfaces of the black-based         foamed product such that a gap is provided between the         black-based stretch film and the black-based foamed product.

<2> The method according to <1>, wherein:

-   -   the step of setting includes the step of placing the cover board         on the pallet; and     -   the black-based foamed product is stacked on the cover board         placed on the pallet.

<3> The method according to <1> or <2>, wherein the black-based stretch film has a thickness of 10 μm to 250 μm and has a solar absorptance of not less than 90% in a visible light range of 380 nm to 720 nm.

<4> The method according to any one of <1> to <3>, wherein the black-based stretch film contains 100 parts by weight of a polyolefin-based resin and 3 parts by weight to 15 parts by weight of carbon black.

<5> The method according to any one of <1> to <4>, wherein the black-based stretch film has ventilation holes.

<6> The method according to <5>, wherein an open hole rate of the ventilation holes per unit area of the black-based stretch film is 1% to 20%.

<7> The method according to any one of <1> to <6>, wherein: the cover board is made of at least one selected from the group consisting of a wooden board, a corrugated board, a plastic corrugated board, and a synthetic resin board; and the cover board has a thickness of not less than 1 mm.

<8> The method according to any one of <1> to <7>, wherein the step of setting includes the step of interposing the cover board between the layers into which the black-based foamed product has been stacked.

<9> The method according to any one of <1> to <8>, wherein the gap between the black-based stretch film and the black-based foamed product is not less than 5 mm.

<10> A package including:

-   -   a black-based foamed product stacked in one or more layers on a         pallet and made of a thermoplastic resin, the black-based foamed         product having a rectangular shape and having a lightness index         L* of less than 65;     -   a cover board which is set on the black-based foamed product         such that the cover board covers a main surface of at least an         uppermost layer of the black-based foamed product, the cover         board having a larger dimension than the black-based foamed         product; and     -   a black-based stretch film covering an outer periphery         corresponding to side surfaces of the cover board and an outer         periphery corresponding to side surfaces of the black-based         foamed product such that a gap is provided between the         black-based stretch film and the black-based foamed product.

EXAMPLES

The following will describe Examples, Comparative Examples, and Reference Examples, but these Examples, Comparative Examples, and Reference Examples do not limit the present invention.

[Materials]

The following describes materials that were used in Examples, Comparative Example, and Reference Examples.

(Foamed Products)

Foamed product A: Black-based expanded polystyrene-based resin foamed molded product (expanding ratio: 80 times, lightness index: 48, size: 909 in width×1,818 mm in length×50 mm in thickness) Foamed product B: White-based expanded polystyrene-based resin foamed molded product (expanding ratio: 80 times, lightness index: 91, size: 909 mm in width×1,818 mm in length×50 mm in thickness)

(Cover Board)

Cover board A: Wooden cover board (size: 1,000 mm in width×1,920 mm in length×10 mm in thickness) Cover board B: Plastic corrugated board (size: 1,000 mm in width×1,920 mm in length×14 mm in thickness, TECCELL T14-3200 produced by Gifu Plastic Industry Co., Ltd.)

(Stretch Film)

Black stretch film: Dia stretch film; color stretch film BA (black)

Product number: TK-30420BLACK

Thickness: 20 μm×width: 500 mm×(length: 300 m)

Solar absorptance: 95%, produced by TSUKASA CHEMICAL INDUSTRY CO., LTD.

Transparent stretch film: Dia stretch film

Product number: TK-30000

Thickness: 20 μm×width: 500 mm×(length: 300 m)

Solar absorptance: 0%, produced by TSUKASA CHEMICAL INDUSTRY CO., LTD.

(Pallet)

Pallet: Wooden pallet (size: 1,100 mm in width×2,000 mm in length×150 mm in thickness)

[Measuring Method]

The following will describe an evaluating method that was carried out in Examples, Comparative Examples, and Reference Examples.

(Solar Absorptance)

The solar absorptance of a stretch film was measured by the method described in (1) to (5) below: (1) A black-based stretch film was prepared as a measurement test piece, and reflectances (spectral reflectances) at respective wavelengths in the wavelength range of 380 nm to 720 nm were measured every 1 nm with use of a self-recording spectrophotometer on the premise that a reflectance of an alumina white substrate was 100%; (2) with use of Appendix 3 of JIS A5759, respective values were calculated by multiplying the spectral reflectances at the respective wavelengths measured in (1) by respectively corresponding weighting coefficients at the wavelengths, and a solar reflectance was calculated as a sum of the values thus obtained (spectral solar reflectance test method); (3) transmittances (spectral transmittances) at the respective wavelengths were measured, for the measurement test piece in (1), with use of the self-recording spectrophotometer on the premise that the transmittance in a state where the measurement test piece was absent in the self-recording spectrophotometer was 100%; (4) with use of Appendix 3 of JIS A5759, respective values were calculated by multiplying the spectral transmittances at the respective wavelengths measured in (3) by the respectively corresponding weighting coefficients at the wavelengths, and a solar transmittance was calculated as a sum of the values thus obtained; and (5) with use of a resultant value of the solar reflectance and a resultant value of the solar transmittance, the solar absorptance was calculated by the following formula (1):

(Solar absorptance)=100%−(solar reflectance)−(solar transmittance)   (1).

(Stacking Stability)

Visually checked was a state of a package while the package was being carried for 3 minutes with use of a forklift, and stacking stability in the package was evaluated on the basis of criteria below.

GOOD: No problem such as stack collapse occurs.

POOR: A problem such as stack collapse occurs, and re-stacking in the package was necessary.

(Exposure Test)

An exposure test by leaving the package outside was carried out as below. Each of packages prepared in Examples, Comparative Examples, and Reference Examples was left to stand outdoors, and exposed from Aug. 10, 2020 to Aug. 17, 2020. In this period of time, an average ambient temperature was 31.4° C.; the lowest ambient temperature was 24.7° C.; and the highest ambient temperature was 40.5° C.

During the exposure test, a temperature of a foamed product in the package was measured with use of equipment below and a temperature history of the foamed product was obtained by measurement with use of a thermocouple at intervals of 15 minutes; and an obtained highest temperature of the foamed product during the exposure test was considered as a highest surface temperature.

Thermocouple: K thermocouple, EA742HD-32 produced by ESCO CO., LTD. Temperature logger: midi LOGGER GL840 (20 point type) produced by GRAPHTEC CORPORATION

After the exposure had been ended, the foamed product was taken out of the package. Then, a surface property and a shape of the foamed product, and an appearance of the foamed product were evaluated by a method below.

(Evaluation of Surface Property and Shape of Packed Foamed Product)

The foamed product having been subjected to the exposure test was visually checked, and the surface property and the shape of the foamed product were evaluated on the basis of criteria below.

GOOD: No abnormality was observed in beads constituting the foamed product.

POOR: Enlargement and/or melting of beads constituting the foamed product was observed.

(Appearance of Packed Foamed Product)

The foamed product having been subjected to the exposure test was visually checked, and an appearance of the foamed product was evaluated on the basis of the criteria below.

GOOD: No dirt was observed on a surface of the foamed product.

POOR: Dirt was found on the surface of the foamed product.

Example 1

On a cover board A (lower cover board A) that had been placed on a pallet, foamed products A (lower foamed products A) stacked in respective four layers on top of each other were placed. Further, another cover board A (center cover board A) was placed on the lower foamed products A. After that, on the center cover board A, other foamed products A (upper foamed products A) stacked in respective four layers on top of each other were further placed. Further, on the upper foamed products A, a cover board A (upper cover board A) was set (the stacking order from the bottom was as follows: the pallet made of polypropylene; the lower (underlay) cover board A; the lower foamed products A (four layers); the middle (center) cover board A; the upper foamed products A (four layers); and the upper (uppermost) cover board A). Subsequently, the thermocouple was attached to substantially a center (in a length direction and a thickness direction) of a side surface on a length side of the upper foamed products A. Thereafter, side surfaces of a stack constituted by the foamed products A and the cover boards A were covered with a black stretch film in a vertical (height) direction from side surface portions of the pallet such that the black stretch film was wound for three turns on side walls of the stack (so as to make three layers of the black stretch film present at any one point on the side walls of the stack). As a result, a package was obtained. With respect to the package, the stacking stability test and the exposure test of leaving the package outside were carried out, and a highest surface temperature was measured. Finally, the following were evaluated: stacking stability; the surface property and shape of the packed foamed product, and the appearance of the packed foamed product. Table 1 shows the result of evaluation.

Example 2

A package was obtained as in Example 1 except that, instead of winding the black stretch film for three turns, the side walls of the stack were covered with the black stretch film such that the black stretch film was wound on the side walls of the stack for a single turn (so as to make one layer of the black stretch film present at any one point on the side walls of the stack) and then was further covered with a transparent stretch film such that the transparent film was wound on the black stretch film for two turns (so as to make two layers of the transparent stretch film present at any one point on the side walls of the stack). Physical properties of the packed foamed product were then measured and evaluated. Table 1 shows the result of measurement.

Example 3

A package was obtained as in Example 1 except that, as a cover board, a cover board B was used instead of the cover board A. Physical properties of the of the packed foamed product were then measured and evaluated. Table 1 shows the result of measurement.

Example 4

A package was obtained as in Example 1 except that the black stretch film was perforated with use of a hot needle, and that ventilation holes (hole diameter: φ1 mm, hole arrangement: staggered arrangement, open hole rate: 5%) were formed. Physical properties of the packed foamed product were then measured and evaluated. Table 1 shows the result of measurement.

Comparative Example 1

A package was obtained as in Example 1 except that the side walls of the stack were covered with use of a transparent stretch film without the black stretch film, such that the transparent stretch film was wound on the side walls of the stack for three turns (such that the transparent stretch film was wound so as to make three layers of the transparent stretch film present at any point on the side walls of the stack). Physical properties of the packed foamed product were then measured and evaluated. Table 1 shows the result of measurement.

Comparative Example 21

A package was obtained as in Example 1 except that no stretch film was used (the stack was not covered). Physical properties of the packed foamed product were then measured and evaluated. Table 1 shows the result of measurement. Note that a surface of the foamed product having been subjected to the exposure test exhibited adhesion of dirt due to fugitive dust.

Comparative Example 3

A package was obtained as in Example 1 except that no cover board A (none of lower cover board, middle cover board, and upper cover board) was used. Physical properties of the packed foamed product were then measured and evaluated. Table 1 shows the result of evaluation.

Reference Example 11

A package was obtained as in Example 1 except that the foamed products B were stacked instead of the foamed products A and that the side walls of the stack were covered, with the transparent stretch film instead of the black stretch film, such that the transparent stretch film was wound on side walls of the stack for three turns (such that the transparent stretch film was wound so as to make three layers of the transparent stretch film present at any point on the side walls of the stack). Physical properties of the packed foamed product were then measured and evaluated. Table 1 shows the result of evaluation.

Reference Example 21

A package was obtained as in Example 1 except that the foamed products B were stacked instead of the foamed products A. Physical properties of the packed foamed product were then measured and evaluated. Table 1 shows the result of measurement.

TABLE 1 Comp. Comp. Comp. Ref. Ref. Ex. Ex. 1 Ex. 2 Ex 3 Ex. 4 Ex. 1 Ex. 2 Ex. 3 Ex 1 2 Package Foamed product Foamed Foamed Foamed Foamed Foamed Foamed Foamed Foamed Foamed configuration product product product product product product product product product A A A A A A A B B Stretch film Black Black + Black Black Trans- — Black Trans- Black transparent (porous) parent parent Cover board Cover Cover Cover Cover Cover Cover — Cover Cover board A board A board B board A board A board A board A board A Physical Stacking stability Good Good Good Good Good Poor Good Good Good properties Highest surface 70.5 74.2 70.7 68.3 91.3 73.3 87.1 65.5 50.5 temperature Surface property Good Good Good Good Poor Good Poor Good Good and shape of foamed product Appearance of Good Good Good Good Good Poor Good Good Good foamed product Total evaluation Good Good Good Good Poor Poor Poor Good Good

[Results]

The followings are clear from Table 1.

(1) A comparison between each of Examples 1 to 4 (Ex. 1 to Ex. 4) and Comparative Example 1 (Comp. Ex. 1) shows that as compared with a case where a conventional transparent stretch film is used for packing, the present packing method makes it possible by packing with use of a black stretch film to reduce deterioration in surface property and shape of a foamed product, such as enlargement of beads which constitute a packed foamed product and surface melting of the foamed product.

(2) A comparison between each of Examples 1 to 4 and Comparative Example 2 (Comp. Ex. 2) shows that in a case where no stretch film is used for packing, the stacking stability of a packed material is poor, and in the case of fake leaving, dirt is adhered to a surface of the foamed product, resulting in a poor appearance.

(3) A comparison between each of Examples 1 to 4 and Comparative Example 3 (Comp. Ex. 3) shows that, in a case where no cover board is set, a black stretch film directly touches a foamed product in a package, and this results in rise in temperature of the foamed product and consequently in a poor surface property and a poor shape of the foamed product due to, for example, enlargement of beads.

(4) The results of Reference Examples 1 and 2 (Ref. Ex. 1 and Ref. Ex. 2) show that, in a case where a foamed product is white (in a case where the foamed product is not black-based), packing with use of a transparent stretch film does not cause a problem such as deformation of the foamed product. In this case, the packing method of the present application can also achieve suitable packing.

One or more embodiments of the present invention makes it possible to provide a method which is for packing a black-based foamed product and which can achieve, at a low cost, both stacking stability and reduction of a rise in temperature of the black-based foamed product. The black-based foamed product can be suitably used for applications, such as a heat insulator for housing.

Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present disclosure. Accordingly, the scope of the invention should be limited only by the attached claims Reference Signs List

-   -   1, 1 a, 1 b Black-based foamed product     -   2 a to 2 g Cover board     -   3 Black-based stretch film     -   4 Pallet     -   100 Package 

1. A method for packing, into one package, the method comprising the steps of: setting, on a black-based foamed product that is stacked in one or more layers on a pallet, a cover hoard such that the cover board covers a main surface of at least an uppermost layer of the black-based foamed product, the cover board having a larger dimension than the black-based foamed product; and covering, with a black-based stretch film, an outer periphery corresponding to side surfaces of the cover board and an outer periphery corresponding to side surfaces of the black-based foamed product such that a gap is provided between the black-based stretch film and the black-based foamed product, wherein the package includes the black-based foamed product which has a rectangular shape, which is made of a thermoplastic resin, and which has a lightness index L* of less than
 65. 2. The method according to claim 1, wherein: the step of setting includes the step of placing the cover board on the pallet; and the black-based foamed product is stacked on the cover board placed on the pallet.
 3. The method according to claim 1, wherein the black-based stretch film has a thickness of 10 μm to 250 μm and has a solar absorptance of not less than 90% in a visible light range of 380 nm to 720 nm.
 4. The method according to claim 1, wherein the black-based stretch film contains 100 parts by weight of a polyolefin-based resin and 3 parts by weight to 15 parts by weight of carbon black.
 5. The method according to claim 1, wherein the black-based stretch film has ventilation holes.
 6. The method according to claim 5, wherein an open hole rate of the ventilation holes per unit area of the black-based stretch film is 1% to 20%.
 7. The method according to claim 1, wherein: the cover board is made of at least one selected from the group consisting of a wooden board, a corrugated board, a plastic corrugated board, and a synthetic resin board; and the cover board has a thickness of not less than 1 mm.
 8. The method according to claim 1, wherein the step of setting includes the step of interposing the cover board between the layers into which the black-based foamed product has been stacked.
 9. The method according to claim 1, wherein the gap between the black-based stretch film and the black-based foamed product is not less than 5 mm.
 10. A package comprising: a black-based foamed product stacked in one or more layers on a pallet and made of a thermoplastic resin, wherein the black-based foamed product has a rectangular shape and has a lightness index L of less than 65; a cover board which is set on the black-based foamed product such that the cover hoard covers a main surface of at least an uppermost layer of the black-based foamed product, wherein the cover board has a larger dimension than the black-based foamed product; and a black-based stretch film covering an outer periphery corresponding to side surfaces of the cover board and an outer periphery corresponding to side surfaces of the black-based foamed product such that a gap is provided between the black-based stretch film and the black-based foamed product. 